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  • 251.
    Ebbestad, Jan Ove
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Sunding, Elisabeth
    Excursion Guide 2 - Nærsnes2002Övrigt (Övrig (populärvetenskap, debatt, mm))
  • 252. Egenhoff, Sven
    et al.
    Cassle, Chris
    Maletz, Jörg
    Frisk, Åsa M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Ebbestad, Jan Ove R.
    Uppsala universitet, Enheten för musik och museer, Evolutionsmuseet.
    Stübner, Konstanze
    Sedimentology and sequence stratigraphy of a pronounced Early Ordovician sea-level fall on Baltica - The Bjorkasholmen Formation in Norway and Sweden2010Ingår i: Sedimentary Geology, ISSN 0037-0738, E-ISSN 1879-0968, Vol. 224, nr 1-4, s. 1-14Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Bjorkasholmen Formation consists of interbedded carbonates, shales, and glauconitic beds and is characterized by heavy bioturbation and few preserved sedimentary structures. The unit shows five facies shale, glauconitic packstone, and three predominantly mud-dominated carbonate facies. Carbonates and shales are arranged in small-scale deepening-upward cycles. A minimum of fourteen of these small-scale cycles are recognized in the Bjorkasholmen Formation. They are arranged in stacks of 3 to 5, forming a total of four medium-scale cycles separated by decimeter-thick shale units. Based on the predominance of mud-rich facies the succession is interpreted to have been deposited in an overall tranquil setting during one mayor sea-level fall and subsequent initial rise of third order. Time-estimates suggest that the 14 small-scale cycles fall into the Milankovitch band of precessional forcing, and the overriding medium-scale cycles likely represent short eccentricity. The sequence stratigraphic interpretation shows that the Bjorkasholmen Formation is characterized by failing stage, lowstand and initial transgressive systems tracts. Consequently, the contact between the Bjorkasholmen and the underlying Alum Shale Formation represents the basal surface of forced regression. The maximum regressive surface is defined by a hiatus in the Oland sections and by shallow-marine packstones within mud-rich distal ramp carbonates in Norway. The top of the Bjorkasholmen Formation represents a flooding surface at the base of the transgressive systems tract. A comparison of time-equivalent successions worldwide suggests that the Bjorkasholmen Formation represents a tectonically-enhanced lowstand with two overriding short-term Milankovitch eustatic signals. Although deposition of the Bjorkasholmen Formation coincides with the initiation of a foreland basin in the Caledonides of Norway it remains unclear how these tectonic movements may have lead to the widespread Bjorkasholmen lowstand during the Early Ordovician. It is Suggested in this Study that a combination of compressional forces from Avalonia and the Caledonian margin may have acted in concert to produce an uplift of larger parts of the Baltica plate for a time-span of approximately 0.5 Myr.

     

  • 253. Egenhoff, Sven
    et al.
    Cassle, Christopher
    Maletz, Jörg
    Ebbestad, Jan Ove
    Uppsala universitet, Enheten för musik och museer, Evolutionsmuseet. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Frisk, Åsa M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Tectonically-Induced Lowstand on an Ordovician Ramp – the Björkåsholmen Formation of Scandinavia2008Ingår i: 2008 Houston Annual Meeting (5–9 October 2008).: Geological Society of America Abstracts with Programs, Geological Society of America , 2008, s. 393-Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The Tremadoc Björkåsholmen Formation is an approximately one meter thick unit consisting of several carbonate beds with intercalated shales and some glauconite content in its upper part. It is underlain by the Cambrian-Ordovician Alum Shale Formation throughout Scandinavia, and in Norway and westernmost Sweden overlain by the Lower- to Middle Ordovician Tøyen Formation. The Björkåsholmen Formation is remarkably widespread in Scandinavia with relatively little variation in thickness or faunal composition. Internally, the unit consists of thin beds at the base with thicker ones in the center and again thinner beds towards the top. Thin beds are generally mud-rich while thicker ones display packstones. In the Norwegian sections the grain-rich facies have been mostly diagenetically overprinted, whereas eastern Swedish localities are characterized by much better facies preservation regardless of lithology. The overall mud-rich facies of the Björkåsholmen Formation reflects deposition on a low-inclined ramp environment. Coarse-grained sediments represent the proximal facies while increasing mud content shows deeper water middle to outer ramp deposition. Facies trends indicate that the Björkåsholmen Formation consists of at least five regressions and successive transgressions with a maximum lowstand represented by its coarse-grained central portion. As the Björkåsholmen Formation is sandwiched between two prominent outer shelf shales in the Norwegian and westernmost Swedish localities it also represents the most pronounced sea-level lowstand in the Early Ordovician of Scandinavia.This lowstand is within the upper part of the Aorograptus victoriae Biozone and the basal Kiaerograptus supremus Biozone. Deposition of the Björkåsholmen Formation therefore likely represents a fairly short time-span. However, this remarkably strong lowstand in Scandinavia is not paralleled by base-level falls in Bolivia, China or Newfoundland. It is therefore suggested that the Björkåsholmen Formation reflects a tectonic rather than a eustatic event which is restricted exclusively to Baltoscandia.

  • 254.
    Egerquist, E.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi. PALAEOBIOLOGY.
    New brachiopods from the Lower - Middle Ordovician (Billingen - Volkhov)2003Ingår i: Acta Palaentologica Polonica, Vol. 48, nr 1Artikel i tidskrift (Refereegranskat)
  • 255.
    Egerquist, Eva
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleontologigruppen.
    New brachiopods from the Lower-Middle Ordovician (Billingen-Volkhov stages) of the East Baltic2003Ingår i: Acta Palaeontologica Polonica, ISSN 0567-7920, Vol. 48, nr 1, s. 31-38Artikel i tidskrift (Refereegranskat)
  • 256.
    Egerquist, Eva
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi, Paleontologigruppen.
    Ordovician (Billingen and Volkhov stages) Brachiopod Faunas of the East Baltic2004Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Lower-Middle Ordovician (Arenig) successions in the East Baltic have been investigated for more than one hundred and fifty years. Nevertheless detailed sampling still yields new species and better knowledge of the environment in which these organisms lived. The successions are well suited for bed by bed sampling because of the lack of tectonic disturbance and because the sequences are well documented.

    This study analyses collections of Billingen-Volkhov age mainly from the St. Petersburg region, but also from Estonia. A great deal of the material was obtained from the marly to clayey, soft sediment that intercalates the compact packstones and wackestones in the succession. Twenty-nine of these clay horizons were used for diversity estimates on the fauna through the succession. The most thoroughly investigated groups for this investigation were rhynchonelliformean brachiopods, conodonts and ostracodes. The results indicate that variances in diversity and abundance levels for these groups were not correlated, either to each other or to the small-scale sea level fluctuations that have been suggested for the region. However, diversity dynamics of brachiopods and ostracodes confirm the large-scale upward shallowing of the basin into the Upper Volkhov. Comparison with fossils from the limestones did not reveal any differences in faunal composition between the two preservation modes.

    The detailed sampling, coupled with sampling of the recently described mud mounds that occur in several outcrops, yielded large numbers of specimens. This enabled revision of earlier poorly known rhynchonelliformean genera such as Ujukella Andreev, as well as better known genera such as Porambonites Pander. In total the examined faunas include 31 genera assigned to 53 species of rhynchonelliformean brachiopods. Of these Leoniorthis and Eoporambonites are defined as new genera, and the following new species are described: Neumania paucicostata, Ranorthis rotunda, Orthidium gambolovensis, Orthidium lavensis, Skenidioides minutus, Tetralobula peregrina, Idiostrophia prima and Idiostrophia tenuicostata.

    Delarbeten
    1. Spatial variations in faunal composition, Middle Ordovician, Volkhov Stage, East Baltic
    Öppna denna publikation i ny flik eller fönster >>Spatial variations in faunal composition, Middle Ordovician, Volkhov Stage, East Baltic
    2001 (Engelska)Ingår i: GFF, ISSN 1103-5897, Vol. 123, nr 2, s. 65-72Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Small-scale lateral variations in faunal skeletal composition and taphonomic characters were analysed at five successive levels containing soft clay layers in the Middle Ordovician (Middle and Upper Volkhov Stage) of the Putilovo quarry in the East Baltic region of Russia. At the studied levels, the relative abundance of faunal elements (mainly brachiopods, ostracodes, and conodonts) generally shows high spatial homogeneity. This even faunal composition is probably due to major time averaging, leading to equalisation of the composition of the assemblages within the units. Differences in taphonomic characters between the sub-samples are also mostly minor; variation in the degree of shell breakage is most probably the result of intensive bioturbation rather than of hydraulic transportation. Changes in the relative abundance of taxa either spatially or temporally, can be considered reliable only if they exceed the small-scale spatial heterogeneity of faunal composition as well as the errors related to the sample size and laboratory treatment of the samples. The relative error in the relative abundance of conodont taxa connected with the laboratory treatment is rather high (approximately 12%).

    Nyckelord
    Conodonts, brachiopods, ostracodes, diversity, taphonomy, Ordovician, Russia
    Nationell ämneskategori
    Geovetenskap och miljövetenskap
    Identifikatorer
    urn:nbn:se:uu:diva-91909 (URN)
    Tillgänglig från: 2004-05-14 Skapad: 2004-05-14 Senast uppdaterad: 2013-04-29Bibliografiskt granskad
    2. Faunal composition and dynamics in unconsolidated sediments: a case study from the Middle Ordovician of the East Baltic
    Öppna denna publikation i ny flik eller fönster >>Faunal composition and dynamics in unconsolidated sediments: a case study from the Middle Ordovician of the East Baltic
    Visa övriga...
    2003 (Engelska)Ingår i: Geological Magazine, ISSN 0016-7568, Vol. 140, nr 1, s. 31-44Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    The Volkhov Regional Stage (Middle Ordovician) in the East Baltic preserves diverse fossil assemblages dominated by epibenthic suspension feeders. Brachiopods, ostracodes, conodonts, echinoderms and bryozoans are the main components of palaeocommunities obtained from clay horizons in the Putilovo section (St Petersburg region, Russia), whereas trilobites, machaeridians, hyolithids, graptolites, benthic foraminifers and gastropods are rare or occur sporadically. Brachiopod bioclasts volumetrically dominate the debris of the studied sediments. Quantitative faunal data are used to assess species diversity patterns, as expressed by the species richness (total number of species in the standardized sample size) and by the evenness or equitability of the community. The numerical abundance of particular taxa in each standardized sample was used to evaluate the density of the fauna. The communities in the Volkhov Stage in Putilovo Quarry reveal a remarkable stability throughout the studied interval and are characterized by high density (1000–6000 specimens per 100 g), relatively moderate species richness (10–15 species) and a moderately variable equitability (0.3–0.7) for the dominant fossil groups (conodonts, ostracodes and brachiopods). Ostracodes significantly increase in numbers within the upper part of the section. This confirms a shallowing of the basin during the late Volkhov interval. Small-scale variability of the diversity estimates does not correlate with the small-scale sea-level changes reconstructed for this part of the basin. It may be connected with error in diversity measurement, or the result of undetected environmental parameters. Variability estimates for different faunal groups are poorly correlated because particular groups have different environmental tolerances.

    Nyckelord
    diversity, Conodonta, Brachiopoda, Ostracoda, Ordovician, Baltoscandia
    Nationell ämneskategori
    Geovetenskap och miljövetenskap
    Identifikatorer
    urn:nbn:se:uu:diva-91910 (URN)10.1017/S001675680200701X (DOI)
    Tillgänglig från: 2004-05-14 Skapad: 2004-05-14 Senast uppdaterad: 2013-04-29Bibliografiskt granskad
    3. Conodonts and brachiopods from the Middle Ordovician microbial mud mound at Putilovo Quarry, north-western Russia
    Öppna denna publikation i ny flik eller fönster >>Conodonts and brachiopods from the Middle Ordovician microbial mud mound at Putilovo Quarry, north-western Russia
    2003 Ingår i: Bulletin of the Geological Society of Denmark, ISSN 0011-6297, Vol. 50, nr 1, s. 63-74Artikel i tidskrift (Refereegranskat) Published
    Identifikatorer
    urn:nbn:se:uu:diva-91911 (URN)
    Tillgänglig från: 2004-05-14 Skapad: 2004-05-14Bibliografiskt granskad
    4. New brachiopods from the Lower-Middle Ordovician (Billingen-Volkhov stages) of the East Baltic
    Öppna denna publikation i ny flik eller fönster >>New brachiopods from the Lower-Middle Ordovician (Billingen-Volkhov stages) of the East Baltic
    2003 Ingår i: Acta Palaeontologica Polonica, ISSN 0567-7920, Vol. 48, nr 1, s. 31-38Artikel i tidskrift (Refereegranskat) Published
    Identifikatorer
    urn:nbn:se:uu:diva-91912 (URN)
    Tillgänglig från: 2004-05-14 Skapad: 2004-05-14Bibliografiskt granskad
    5. Revision of the plectambonitoid brachiopod Ujukella Andreev and related genera
    Öppna denna publikation i ny flik eller fönster >>Revision of the plectambonitoid brachiopod Ujukella Andreev and related genera
    1999 Ingår i: GFF, ISSN 1103-5897, Vol. 121, nr 4, s. 325-332Artikel i tidskrift (Refereegranskat) Published
    Identifikatorer
    urn:nbn:se:uu:diva-91913 (URN)
    Tillgänglig från: 2004-05-14 Skapad: 2004-05-14Bibliografiskt granskad
    6. Ordovician (Arenig-Caradoc) Syntrophiidine brachiopods from the East Baltic Region
    Öppna denna publikation i ny flik eller fönster >>Ordovician (Arenig-Caradoc) Syntrophiidine brachiopods from the East Baltic Region
    2005 (Engelska)Ingår i: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983, Vol. 48, nr 4, s. 739-761Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Syntrophiidine brachiopods are a rare and poorly known component of Ordovician Baltoscandian faunas. They appear in the East Baltic in the Billingenian (lower Arenig) as part of the earliest known benthic assemblages dominated by elements of the Palaeozoic Evolutionary Fauna. These faunal assemblages usually include bryozoans, ostracodes, and the earliest known porambonitoids, strophomenides and endopunctate orthides, such as Idiostrophia and Orthidium, which later became characteristic of the Whiterockian brachiopod assemblages in Laurentia, but by that time had disappeared from Baltica. The superfamily Syntrophioidea reappears in Baltoscandia in the mid Caradoc. In contrast, Porambonitoidea remained the integral part of the Baltoscandian brachiopod associations through the Ordovician. Porambonites, herein redefined on the basis of restudy of the type species P. intermedius, includes only smooth porambonitoids; taxa with the distinctive ornament of radiating rows of pits first appeared in the group in the mid Arenig. The taxa Eoporambonites gen. nov., Tetralobula peregrina sp. nov., Idiostrophia prima sp. nov. and Idiostrophia tenuicostata sp. nov. are erected.

    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:uu:diva-91914 (URN)10.1111/j.1475-4983.2005.00487.x (DOI)
    Tillgänglig från: 2004-05-14 Skapad: 2004-05-14 Senast uppdaterad: 2017-12-14Bibliografiskt granskad
    7. Early-Middle Ordovician (Billingen-Volkhov stages) Orthide and Protorthide brachiopods from the East Baltic
    Öppna denna publikation i ny flik eller fönster >>Early-Middle Ordovician (Billingen-Volkhov stages) Orthide and Protorthide brachiopods from the East Baltic
    2006 (Engelska)Ingår i: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 128, nr 4, s. 339-348Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Three new orthide species: Orthidium lavensis, Orthidium gambolovensis and Ranorthis rotunda, and one new protorthide species: Skenidioides minutus, are described from the Early-Middle Ordovician (Billingen-Volkhov stages) of Estonia and north-western Russia. This is the first record of Orthidium from Baltica, whereas Skenidioides was known previously only from the Keila and Oandu stages in Estonia.

    Nyckelord
    Brachiopoda, Estonia, New species, Ordovician, Orthida, Orthidium, Protorthida, Ranorthis, Russia, Skenidioides
    Nationell ämneskategori
    Geovetenskap och miljövetenskap
    Identifikatorer
    urn:nbn:se:uu:diva-91915 (URN)000243752400007 ()
    Tillgänglig från: 2004-05-14 Skapad: 2004-05-14 Senast uppdaterad: 2017-12-14Bibliografiskt granskad
  • 257.
    Egerquist, Eva
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleontologigruppen.
    Revision of the plectambonitoid brachiopod Ujukella Andreev and related genera1999Ingår i: GFF, ISSN 1103-5897, Vol. 121, nr 4, s. 325-332Artikel i tidskrift (Refereegranskat)
  • 258.
    Egerquist, Eva
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi, Paleontologigruppen.
    Holmer, Lars E.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Early-Middle Ordovician (Billingen-Volkhov stages) Orthide and Protorthide brachiopods from the East Baltic2006Ingår i: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 128, nr 4, s. 339-348Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Three new orthide species: Orthidium lavensis, Orthidium gambolovensis and Ranorthis rotunda, and one new protorthide species: Skenidioides minutus, are described from the Early-Middle Ordovician (Billingen-Volkhov stages) of Estonia and north-western Russia. This is the first record of Orthidium from Baltica, whereas Skenidioides was known previously only from the Keila and Oandu stages in Estonia.

  • 259.
    Einarsson, Elisabeth
    et al.
    Lund University.
    Kear, Benjamin P.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    A mid-Campanian marine extinction event – possible evidence from the Kristianstad Basin of southern Sweden2011Ingår i: The 2nd Wiman Meeting. Carl Wiman's Legacy: 100 Years of Swedish Palaeontology / [ed] Benjamin P. Kear and Michael Streng, 2011, s. 7-8Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Potential traces of a mid-Campanian (83–73 Ma) marine extinction event have been documented as sequential faunal turnover in shallow coastal calcareous sands and calcarenite strata at the Åsen locality in the Kristianstad Basin of southern Sweden. The depositional succession at Åsen is conformably divided into the latest-early Campanian Belemnellocamax mammillatus belemnite Zone (a lateral equivalent of the northern European Belemnitella mucronata senior/Gonioteuthis quadrata gracilis Zone), and an overlying earliest-late Campanian Belemnellocamax balsvikensis Zone. The stratigraphically older B. mammillatus Zone assemblages comprise storm-accumulated remains (associated with coquina beds and oyster banks) that include selachians, chimaeroids, bony fish (pachycormiforms, pycnodontids, and teleosts), dyrosaurid crocodilians, elasmosaurid and polycotylid plesiosaurs, mosasaurs (mosasaurines, halisaurines, tylosaurines, and plioplatecarpines), and cheloniid sea turtles. Coeval invertebrates comprise abundant belemnites, bivalves, brachiopods, and echinoderms. This rich biodiversity abruptly declines up-sequence through the oyster bed layer and into the B. balsvikensis Zone; this is characterised by a sandier facies, which is exceptionally poor in reptile remains and manifests only small teleosts and sharks. Benthic molluscs and brachiopods also decline in abundance while worm tracks and decapod crustaceans (crabs) make a first appearance. Although, this observed change clearly corresponds to an environmental shift, it also correlates with a recognised trans-Atlantic mid-Campanian extinction event that affected warm-temperate to sub-tropical palaeolatitudinal belt assemblages in North America, and might have been part of a broader global phenomenon.

  • 260.
    Einarsson, Elisabeth
    et al.
    Lund University.
    lindgren, Johan
    Lund University.
    Kear, Benjamin P.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Siverson, Mikael
    Western Australian Museum.
    Mosasaur bite marks on a plesiosaur propodial from the Campanian (Late Cretaceous) of southern Sweden2010Ingår i: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 132, nr 2, s. 123-128Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Although plesiosaurs and mosasaurs co-existed for about 35 million years at the end of the Cretaceous, the fossil record documenting interactions between these two groups of marine reptiles is meagre. The discovery of deeply incised scars on a limb bone of an immature polycotylid plesiosaur from the latest early Campanian (in the European two-fold division of the Campanian Stage) of the Kristianstad Basin, southern Sweden, is thus significant because it represents a rare example of predation or scavenging on an immature polycotylid plesiosaur by a large mosasaur.

  • 261.
    Elbrächter, Malte
    et al.
    Deutsches Zentrum für Marine Diversitätsforschung.
    Gottschling, Marc
    Department of Geosciences, Oslo university.
    Hildebrand-Habel, Tania
    University of Stavanger.
    Keupp, Helmut
    Abisko Scientific Research Station.
    Kohring, Rolf
    Freie Universität Berlin.
    Lewis, Jane
    University of Westminster.
    Meier, Sebastian
    Christian-Albrechts-Universität zu Kiel.
    Montresor, Marina
    Stazione Zoologica ‘A. Dohrn’, Napoli.
    Streng, Michael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Versteegh, Gerard
    Universität Hamburg.
    Willems, Helmut
    Universität Bremen.
    Zonneveld, Karin
    Universität Bremen.
    Establishing an Agenda for Calcareous Dinoflagellate Research (Thoracosphaeraceae, Dinophyceae) including a nomenclatural synopsis of generic names2008Ingår i: Taxon, ISSN 0040-0262, E-ISSN 1996-8175, Vol. 57, nr 4, s. 1289-1303Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Calcareous dinoflagellates are considered to be a monophyletic group of peridinoid taxa that have the potential to produce calcified exoskeletal structures during the life cycle, or that derive from such forms. Frequently, these calcareous bodies are excellently preserved in the fossil record and have received increased attention during the past three decades with regard to their use in biostratigraphy, climate and environmental reconstruction. Fossil and extant taxa have been classified in various, partly concurring, systematic concepts, using character complexes of the theca, cyst wall ultrastructure and archaeopyle/operculum morphology. The significance of such character complexes is briefly discussed in the light of molecular data that have been accumulated during the past decade. Over the years, the number of published taxonomic names has increased, partly due to nomenclatural changes. We propose that the entirety of calcareous dinoflagellates, and non-calcareous relatives derived from them, is accommodated in a single family of the order Peridiniales, the Thoracosphaeraceae, combining the former segregated taxonomic units Calciodinelloideae, a subfamily within Peridiniaceae, and Thoracosphaerales, a separate dinoflagellate order. As a result of a meeting of calcareous dinoflagellate specialists, we outline major subjects that are in need of re-investigation and -evaluation (an Agenda for Calcareous Dinoflagellate Research). In order to contribute to a consistent and stable nomenclature and taxonomy of calcareous dinoflagellates, we list 97 published generic names assigned to known calcareous dinoflagellates in a nomenclatural synopsis, with species names indicating their types and information on type locality and stratigraphy. We evaluate the status of these names—whether validly published and, if so, whether legitimate—,a crucial first step for any revisionary work in the future.

  • 262. Eliason, Sara
    et al.
    Bassett, Michael
    Willman, Sebastian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Geotourism highlights of Gotland2010Bok (Övrig (populärvetenskap, debatt, mm))
  • 263. Elicki, Olaf
    et al.
    Geyer, Gerd
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    The Cambrian trilobites of Jordan: taxonomy, systematic and stratigraphic significance2013Ingår i: Acta geologica Polonica, ISSN 0001-5709, E-ISSN 2300-1887, Vol. 63, nr 1, s. 1-56Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Elicki, O. and Geyer, G. 2013. The Cambrian trilobites of Jordan - taxonomy, systematic and stratigraphic significance. Acta Geologica Polonica, 63 (1), 1-56. Warszawa. Marine carbonates and siliciclastic rocks of the Burj Formation in Jordan include paucispecific trilobite associations of the (traditional) Lower-Middle Cambrian boundary interval. Comprehensive new material of these trilobites allows a review of their taxonomy and systematic positions as well as a refined morphological description and a reconsideration of previous interpretations of their stratigraphic position and thus the correlation of the fossiliferous beds. In addition to the classic species Kingaspis campbelli (King, 1923) and Redlichops blanckenhorni Richter and Richter, 1941, Timnaella? orientalis (Picard, 1942) and Hesa problematica Richter and Richter, 1941, the discussed trilobites include Issalia gen. nov. with Issalia scutalis gen. nov., sp. nov., Tayanaspis gen. nov. with Tayanaspis bulbosus gen. nov., sp. nov., Uhaymiria gen. nov. with Uhaymiria glabra gen. nov., sp. nov., Cambrunicornia ? jafnaensis sp. nov., Myopsolenites palmeri (Parnes, 1971), M. hyperion sp. nov., and Enixus cf. antiquus (Chernysheva, 1956). Myopsolenites boutiouiti Geyer and Landing, 2004 is now regarded as a junior synonym of Myopsolenites altus (Linan and Gozalo, 1986). A detailed discussion of the correlation with a focus on global aspects provides clues for the utility of potential index fossils for the global Cambrian Series 3 and Stage 5.

  • 264. Elming, Sten-Åke
    et al.
    Moczydlowska, Malgorzata
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi. Palaeobiology.
    Palaeogeography of Baltica in the Cryogenian-Neoproterozoic: palaeomagnetic and palaeontological constraints.2005Ingår i: National Conference on the International Geoscience Programme (IGCP), May 20th, 2005, Uppsala, 2005Konferensbidrag (Övrigt vetenskapligt)
  • 265.
    Eriksson, B. J.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi. PALAEOBIOLOGY.
    Budd, G. E.
    The cephalic nerves of the Onychophora and their bearing on our understanding of head segmentation and stem-group evolution of Arthorpoda2003Övrigt (Övrigt vetenskapligt)
  • 266.
    Eriksson, BJ
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Tait, NN
    Budd, Graham E
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Head development in the onychophoran Euperipatoides kanangrensis with particular reference to the central nervous system2003Ingår i: JOURNAL OF MORPHOLOGY, Vol. 255, nr 1, s. 1-23Artikel i tidskrift (Refereegranskat)
  • 267. Eriksson, BJ
    et al.
    Tait, NN
    Norman, JM
    Budd, Graham E.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    An ultrastructural investigation of the hypocerebral organ of the adult Euperipatoides kanangrensis (Onychophora, Peripatopsidae)2005Ingår i: ARTHROPOD STRUCTURE & DEVELOPMENT, Vol. 34, nr 4, s. 407-418Artikel i tidskrift (Refereegranskat)
  • 268.
    Eriksson, Bo Joakim
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Tait, Noel N.
    Budd, Graham E.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Janssen, Ralf
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Akam, Michael
    Head patterning and Hox gene expression in an onychophoran and its implications for the arthropod head problem2010Ingår i: Development, Genes and Evolution, ISSN 0949-944X, E-ISSN 1432-041X, Vol. 220, nr 3-4, s. 117-122Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The arthropod head problem has puzzled zoologists for more than a century. The head of adult arthropods is a complex structure resulting from the modification, fusion and migration of an uncertain number of segments. In contrast, onychophorans, which are the probable sister group to the arthropods, have a rather simple head comprising three segments that are well defined during development, and give rise to the adult head with three pairs of appendages specialised for sensory and food capture/manipulative purposes. Based on the expression pattern of the anterior Hox genes labial, proboscipedia, Hox3 and Deformed, we show that the third of these onychophoran segments, bearing the slime papillae, can be correlated to the tritocerebrum, the most anterior Hox-expressing arthropod segment. This implies that both the onychophoran antennae and jaws are derived from a more anterior, Hox-free region corresponding to the proto and deutocerebrum of arthropods. Our data provide molecular support for the proposal that the onychophoran head possesses a well-developed appendage that corresponds to the anterior, apparently appendage-less region of the arthropod head.

  • 269. Eriksson, Mats E.
    et al.
    Frisk, Åsa M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Marine astrobleme palaeoecology in the early Late Ordovician of Sweden  Manuskript (preprint) (Övrig (populärvetenskap, debatt, mm))
  • 270. Eriksson, Mats E.
    et al.
    Frisk, Åsa M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Polychaete palaeoecology in an early Late Ordovician marine astrobleme of Sweden2011Ingår i: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 148, nr 2, s. 269-287Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The post-impact Dalby Limestone (Kulcruse; Upper Ordovician) of the Tvaren crater, southeastern Sweden, has been analysed with regards to polychaetes, as represented by scolecodonts. A palaeoecological succession is observed in the Tvaren-2 drill core sequence, as the vacant ecospace was successively filled by a range of benthonic, nektonic and planktonic organisms. Scolecodonts belong to the first non-planktonic groups to appear and constitute one of the most abundant fossil elements. The polychacte assemblage recorded has an overall composition characteristic of that of the Upper Ordovician of Baltoscandia. Oenonites, Vistulella, Mochtyella and the enigmatic 'Xanioprion' represent the most common genera, whereas Pteropelta, Protarabellites?, Atraktoprion and Xanioprion are considerably more rare. The assemblage differs from coeval ones particularly in its poorly represented ramphoprionid fauna and the relatively high frequency of 'Xanioprion'. A taxonomic succession and changes in abundance and relative frequency of different taxa is observed from the deepest part of the crater and upwards towards more shallow water environments. The initial post-impact assemblage does not, however, necessarily represent a benthonic colonization of the crater floor. Instead it seems to be a taphocoenosis, as indicated by its taxonomic correspondence to the rim facies fauna recovered from Dalby Limestone erratics of the Ringson island. The Tvaren succession has yielded considerably richer scolecodont assemblages than hitherto recorded from the approximately coeval Lockne crater, possibly as a consequence of shallower water settings in the former area.

  • 271. Eriksson, Mats E.
    et al.
    Frisk, Åsa M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi, Paleontologigruppen. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Polychaetes from the Kukruse (early Late Ordovician) post-impact event strata of Tvären, southeastern Sweden2009Konferensbidrag (Refereegranskat)
  • 272.
    Felitsyn, S
    et al.
    Institute of Precambrian Geology and Geochronology, Russian Academy of Science, St. Petersburg, Russia .
    Sturesson, U
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Popov, L
    All-Russian Scientific Research Geological Institute, St. Petersburg, Russia .
    Holmer, L
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Nd isotope composition and rare earth element distribution in early Paleozoic biogenic apatite from Baltoscandia: A signature of Iapetus ocean water1998Ingår i: Geology, ISSN 0091-7613, E-ISSN 1943-2682, Vol. 26, nr 12, s. 1083-1086Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Analyses of the Nd isotopic composition and REE distribution in biogenic apatite (organophosphatic brachiopods and conodont elements) from the Cambrian and Ordovician sequences of the Baltic plate give new insights into the development of the southeastern segment of the continental margin bounding the Iapetus ocean. The Nd isotope analyses show ϵNd(t) of ∼−8.0 for the Cambrian, indicating that the main source of the sedimentary deposition came from weathered sedimentary rocks of Vendian and Cambrian age. The increase of ϵNd(t) to ∼−5.0 for the Early Ordovician indicates the appearance of a new source of radiogenic Nd in the surrounding area—most likely a volcanic arc along the western borderland of Baltic plate from Arenigian time. Samples of Cambrian biogenic apatite show significantly lower total amounts of REE than do the Ordovician samples, and this is probably due to a shorter exposure to seawater before burial during Ordovician sedimentary accumulation in Baltoscandia. These preliminary results suggest that biogenic apatite from the Baltoscandian basin preserves geochemical signatures of the water masses that will be important for understanding the evolution of the Iapetus ocean during the early Paleozoic.

  • 273.
    Fischer, Antje H. L.
    et al.
    European Molecular Biology Laboratory.
    Arboleda, Enrique
    Stazione Zoologica Anton Dohrn.
    Egger, Bernhard
    University College London.
    Hilbrant, Maarten
    University of Köln.
    McGregor, Alistair P.
    University of Vienna.
    Cole, Alison G.
    Stazione Zoologica Anton Cohrn.
    Daley, Allison C.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi, Paleontologigruppen.
    ZOONET: perspectives on the evolution of animal form. Meeting report2009Ingår i: Journal of Experimental Zoology, ISSN 0022-104X, E-ISSN 1097-010X, Vol. 312B, nr 7, s. 679-685Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    What drives evolution? This was one of the main questions raised at the   final ZOONET meeting in Budapest, Hungary, in November 2008. The   meeting marked the conclusion of ZOONET, an EU-funded Marie-Curie   Research Training Network comprising nine research groups from all over   Europe (Max Telford, University College London; Michael Akam,   University of Cambridge; Detlev Arendt, EMBL Heidelberg; Maria Ina   Arnone, Stazione Zoologica Anton Dohrn Napoli; Michalis Averof, IMBB   Heraklion; Graham Budd, Uppsala University; Richard Copley, University   of Oxford; Wim Damen, University of Cologne; Ernst Wimmer, University   of Gottingen). ZOONET meetings and practical courses held during the   past four years provided researchers from diverse   backgrounds-bioinformatics, phylogenetics, embryology, palaeontology,   and developmental and molecular biology-the opportunity to discuss   their work under a common umbrella of evolutionary developmental   biology (Evo Devo). The Budapest meeting emphasized in-depth   discussions of the key concepts defining Evo Devo, and bringing   together ZOONET researchers with external speakers who were invited to   present their views on the evolution of animal form. The discussion   sessions addressed four main topics: the driving forces of evolution,   segmentation, fossils and phylogeny, and the future of Evo Devo.

  • 274. Flores, Jose-Abel
    et al.
    Colmenero-Hidalgo, Elena
    Mejia-Molina, Alejandra E.
    Baumann, Karl-Heinz
    Henderiks, Jorijntje
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Larsson, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Prabhu, C. N.
    Sierro, Francisco J.
    Rodrigues, Teresa
    Distribution of large Emiliania huxleyi in the Central and Northeast Atlantic as a tracer of surface ocean dynamics during the last 25,000 years2010Ingår i: Marine Micropaleontology, ISSN 0377-8398, E-ISSN 1872-6186, Vol. 76, nr 3-4, s. 53-66Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The coccolithophore species Emiliania huxleyi is characterized by a wide range of sizes. which can be easily distinguished in the light microscope. In this study we have quantified the abundance of large (coccoliths >4 mu m in maximum length) E. huxleyi specimens during the last 25 kyr in sedimentary records from eleven cores and drill sites in the NE Atlantic and W Mediterranean Sea, to prove its usefulness in the reconstruction of water mass dynamics and biostratigraphic potential. During the Last Glacial Maximum this large form, a cold-water indicator, was common in the NE Atlantic and Mediterranean, and its regional variation in abundance indicates a displacement of the climatic zones southwards in agreement with the development of ice sheets and sea ice in the Northern Hemisphere during this period. On the other hand, the gradient between northern and southern surface water masses in the Subtropical Gyre appears to have been more pronounced than at present, while the Portugal and Canary Currents were more intense. In the western Mediterranean basin temperatures were cooler than in the adjacent Atlantic, provoking a quasi-endemism of these specimens until the end of Heinrich Event 1. This may have been due to a restriction in the communication between the Atlantic and Mediterranean through the Strait of Gibraltar, the arrival of cold surface water and the amplification of cooling after the development of ice sheets in the Northern Hemisphere. During the deglaciation, large E. huxleyi specimens decreased in abundance at medium and low latitudes, but were still numerous close to the Subarctic region during the Holocene. In transitional waters this decrease to present day abundances occurred after Termination lb. The abrupt change in abundance of this large E. huxleyi form is proposed as a new biostratigraphic event to characterize the Holocene in mid- to low-latitude water masses in the North Atlantic, although this horizon seems to be diachronous by 5 kyr from tropical to subarctic regions, in agreement with the gradual onset of warm conditions.

  • 275. Fontana, S. L.
    et al.
    Bennett, Keith D.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Postglacial vegetation dynamics of western Tierra del Fuego2012Ingår i: The Holocene, ISSN 0959-6836, E-ISSN 1477-0911, Vol. 22, nr 11, s. 1337-1350Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The southern fringes of the South American landmass provide a rare opportunity to examine the development of moorland vegetation with sparse tree cover in a wet, cool temperate climate of the Southern Hemisphere. We present a record of changes in vegetation over the past 17,000 years, from a lake in extreme southern Chile (Isla Santa Inés, Magallanes region, 53°38.97S; 72°25.24W), where human influence on vegetation is negligible. The western archipelago of Tierra del Fuego remained treeless for most of the Lateglacial period; Lycopodium magellanicum, Gunnera magellanica and heath species dominated the vegetation. Nothofagus may have survived the last glacial maximum at the eastern edge of the Magellan glaciers from where it spread southwestwards and established in the region at around 10,500 cal. yr BP. Nothofagus antarctica was likely the earlier colonizing tree in the western islands, followed shortly after by Nothofagus betuloides. At 9000 cal. yr BP moorland communities expanded at the expense of Nothofagus woodland. Simultaneously, Nothofagus species shifted to dominance of the evergreen Nothofagus betuloides and the Magellanic rain forest established in the region. Rapid and drastic vegetation changes occurred at 5200 cal. yr BP, after the Mt Burney MB2 eruption, including the expansion and establishment of Pilgerodendron uviferum and the development of mixed Nothofagus-Pilgerodendron-Drimys woodland. Scattered populations of Nothofagus, as they occur today in westernmost Tierra del Fuego may be a good analogue for Nothofagus populations during the Lateglacial in eastern sites.

  • 276.
    Fontana, Sonia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Holocene vegetation history and palaeoenvironmental conditions on the temperate Atlantic coast of Argentina, as inferred from multi-proxy lacustrine records2005Ingår i: Journal of Paleolimnology, Vol. 34, s. 445-469Artikel i tidskrift (Refereegranskat)
  • 277.
    Fontana, Sonia L.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi. Palaeobiology.
    A new giant cypridid ostracod (Crustacea) from southern Buenos Aires Province, Argentina2005Ingår i: Hydrobiologia, ISSN 0018-8158, Vol. 533, nr 1, s. 187-197Artikel i tidskrift (Refereegranskat)
  • 278.
    Fontana, Sonia L.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi. Palaeobiology.
    Coastal dune vegetation and pollen representation in south Buenos Aires Province, Argentina2005Ingår i: Journal of Biogeography, ISSN 0305-0270, Vol. 32, nr 4, s. 719-735Artikel i tidskrift (Refereegranskat)
  • 279.
    Fontana, Sonia L.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Pollen deposition in coastal dunes, south Buenos Aires Province, Argentina2003Ingår i: Review of Palaeobotany & Palynology, Vol. 126, nr 1-2, s. 17-37Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Modern pollen deposition and its relationship to the surrounding vegetation have been studied in order to help interpret vegetation change during the Holocene on the south coast of Buenos Aires, Argentina. Pollen has been monitored monthly with two Tauber

  • 280.
    Fontana, Sonia L.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Radiocarbon chronologies of Holocene lacustrine sediments from the southern coast of Buenos Aires Province, Argentina2007Ingår i: Radiocarbon, ISSN 0033-8222, E-ISSN 1945-5755, Vol. 49, nr 1, s. 103-116Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Two lacustrine sediment sequences, La Olla 1 and Laguna del Sauce Grande, on the southern coast of Buenos Aires Province, Argentina, were investigated for carbon reservoir effects, which may influence age-depth chronologies. Fruits of the submerged macrophyte Ruppia cf. maritima from the La Olla 1 sequence, and gastropod shells of Heleobia parchappii from the Laguna del Sauce Grande core, were radiocarbon dated. In addition, terrestrial plant remains and shells of living specimens were dated to assess the presence and magnitude of a reservoir effect. A reservoir age of about 800 14C yr is estimated for the aquatic plant samples of La Olla 1 for the early Holocene. The reservoir effect is attributed to the inwash of 14C-deficient bicarbonate from the surrounding sand dunes. The decay of marine organisms and salt spray are likely the main sources of 14C-deficient carbon. The magnitude of the reservoir effect is consistent with marine reservoir offsets reported for the region. The 14C measurements on shells of living and fossil specimens of Heleobia parchappii indicate the absence of a reservoir effect at Laguna del Sauce Grande, which may be due to the large size and shallow nature of the lake. This study shows how the reservoir ages of 2 close-by lakes in very similar geological settings can be largely different. These results have significant implications for the interpretation of 14C dates from lacustrine deposits in the region.

  • 281. Fontana, Sonia L.
    et al.
    Martha Bianchi, Maria
    Bennett, Keith D.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Palaeoenvironmental changes since the Last Glacial Maximum: Patterns, timing and dynamics throughout South America2012Ingår i: The Holocene, ISSN 0959-6836, E-ISSN 1477-0911, Vol. 22, nr 11, s. 1203-1206Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    The vast diversity of present vegetation and environments that occur throughout South America (12 degrees N to 56 degrees S) is the result of diverse processes that have been operating and interacting at different spatial and temporal scales. Global factors, such as the concentration of CO2 in the atmosphere, may have been significant for high altitude vegetation during times of lower abundance, while lower sea levels of glacial stages potentially opened areas of continental shelf for colonisation during a substantial portion of the Quaternary. Latitudinal variation in orbital forcing has operated on a regional scale. The pace of climate change in the tropics is dominated by precessional oscillations of c. 20 kyr, while the high latitudes of the south are dominated by obliquity oscillations of c. 40 kyr. In particular, seasonal insolation changes forced by precessional oscillations must have had important consequences for the distribution limits of species, with potentially different effects depending on the latitude. The availability of taxa, altitude and human impact, among other events, have locally influenced the environments. Disentangling the different forcing factors of environmental change that operate on different timescales, and understanding the underlying mechanisms leads to considerable challenges for palaeoecologists. The papers in this Special Issue present a selection of palaeoecological studies throughout South America on vegetation changes and other aspects of the environment, providing a window on the possible complexity of the nature of transitions and timings that are potentially available.

  • 282.
    Franzen, L. G.
    et al.
    Univ Gothenburg, Dept Earth Sci, SE-40530 Gothenburg, Sweden..
    Malmgren, Björn A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Microscopic charcoal and tar (CHAT) particles in peat: a 6500-year record of palaeo-fires in southern Sweden2012Ingår i: Mires and Peat, ISSN 1819-754X, E-ISSN 1819-754X, Vol. 10, artikel-id 01Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Peat stratigraphies of eleven raised bogs in southern Sweden were investigated. Measurements included the occurrence of charcoal and various tar particles. Most of the particles found were microscopic, i.e. 5-100 mu m in diameter. Two distinctly different groups of particles were distinguished: (A) charred fragments of plant tissue and (B) objects formed from tar, which were classified into five sub-groups on the basis of morphology. Both charcoal and tar are indicative of mire and forest fires. We suggest that it is possible to use the different groups of particles as fire regime indicators. Hence, the high frequency of charcoal and tar (CHAT) in the lower parts of the stratigraphies, i.e. in the lower strongly decomposed fen and carr peats that were formed before ca. 4000 cal C-14 BP, could be indicative of intense and frequent local fires. The decreasing abundance of CHAT and the lower relative share of Type A particles within the lower strongly decomposed Sphagnum peat ca. 4000-2500 cal C-14 BP signify a transition from local to regional fires. With a few exceptions, the uppermost weakly decomposed ombrotrophic peats formed after ca. 2500 cal C-14 BP, in which both charcoal and tar are rare, indicate a period of low fire frequency at both local and regional scales. There is no regional variation in the lower material, and it seems that wildfires were common phenomena throughout southern Sweden during the first few thousand years after peat formation began 6-8000 years ago. From a climatological point of view, the mass occurrence of CHAT in the lower parts of the profiles indicates a warm and dry Mid Holocene with frequent and widespread wildfires, and a moist and cool Late Holocene with more sporadic fires. Spectral analysis of the entire dataset shows significant periodicities of 610, 70, 30, 21, 17 and 14 years, the two most significant being 14 and 70 years.

  • 283.
    Freeman, Rebecca
    et al.
    Missouri State University.
    Miller, James
    Missouri State University.
    Holmer, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Streng, Michael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Linguate brachiopod extinction and global migration coinciding with three laurentian trilobite extinction events during the late cambrian-earliest ordovician2011Ingår i: GSA Annual Meeting in Minneapolis, Minnesota USA, 2011, s. 543-543Konferensbidrag (Refereegranskat)
    Abstract [en]

    Laurentian lingulate brachiopods on the outer shelf were affected by a series of three extinction events coinciding with trilobite extinctions (biomere boundaries). There was rapid turnover of the brachiopod faunas during each event. These extinctions are seen at the Steptoean/Sunwaptan, Sunwaptan/Skullrockian, and Skullrockian/Stairsian North American Upper Cambrian–lowest Ordovician stage boundaries. Lingulate brachiopods were examined from the Orr, Notch Peak, House, and Fillmore formations of western Utah and from the Catlin Formation and Hales Limestone of Nevada. Associated with each extinction event, brachiopod genera/species appeared that are also found in coeval strata in Kazakhstan and/or western Gondwana (e.g., Quadrisonia minorZhanatella rotunda, and species of Eurytreta). Some of these taxa may have appeared in the deeper water/higher latitude environments of Kazakhstan or Gondwana before appearing on the Laurentian shelf. Eurytreta may have appeared in deep-water slope environment at Tybo Canyon, Nevada before appearing in shelf environments in Utah.

    The Steptoean/Sunwaptan and Sunwaptan/Skullrockian boundaries were also examined in the Wilberns and Tanyard formations of central Texas. Latest Steptoean strata yield taxa widely distributed in Laurentia, although endemic to it, such as Linnarssonella girtyi. There is abrupt faunal change at the base of the Sunwaptan, followed by a fauna that is also endemic to Laurentia and is virtually identical to a fauna described from the Snowy Range Formation of Wyoming and Montana. This fauna is not present in coeval strata in Utah and Nevada. Mid-Sunwaptan strata in Texas yield a fauna with strong affinities to coeval strata in Utah; all species are endemic to Laurentia. The Sunwaptan/Skullrockian boundary is also characterized by complete turnover, this time with a replacement fauna having affinities both to the Laurentian outer shelf and to Gondwana and Kazakhstan.

    This pattern of events suggests that Late Cambrian–earliest Ordovician extinctions in Laurentia were caused by environmental changes that altered conditions on the Laurentian shelf to conditions more similar to those in deeper water (Kazakhstan) or higher latitudes (Gondwana), and these changes facilitated migration of globally distributed lingulate brachiopods.

  • 284. Friedman, M.
    et al.
    Blom, H.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi, Paleontologigruppen.
    Ahlberg, Per E.
    New light on the lower jaw of the Devonian tetrapod Elginerpeton2003Ingår i: 51st symposium of vertebrate palaeontology and comparative anatomy, Oxford University Museum of Natural History, Oxford, 2003, s. 35-36Konferensbidrag (Refereegranskat)
  • 285.
    Frisk, Åsa
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Post-impact sediments in the Lockne and Tvären craters, Sweden: facies distribution and gastropod-like molluscs2006Licentiatavhandling, monografi (Övrigt vetenskapligt)
  • 286.
    Frisk, Åsa
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi. Paleobiologi.
    The Bjorkåsholmen Formation (Tremadoc): a homogenous distribution of Trilobites throughout the Baltoscandian platform2005Ingår i: Lundadagarna i Historisk geologi och paleontologi IX, 2005Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    THE BJØRKÅSHOLMEN FORMATION (TREMADOC): A HOMOGENOUS DISTRIBUTION OF TRILOBITES THROUGHOUT THE BALTOSCANDIAN PLATFORM

    Åsa Frisk

    Uppsala University, Department of Earth Sciences, Palaeobiology, Norbyvägen 22, SE-752 36 Uppsala, Sweden.

    Extensive carbonate depositions initiate the Lower Ordovician succession of Baltoscandia forming the Tremadoc Bjørkåsholmen Formation, formerly the Ceratopyge Limestone, a distinctive unit corresponding to the trilobite zone of Apatokephalus serratus. In older studies a combined bio-litho stratigraphical concept of the unit has mostly been used, however a modern lithostratigraphical definition was given by Owen et al. (1990). The definition of the formation is based on the hypostratotype at Bjørkåsholmen in Slemmestad, Norway, and should be referred to instead of the historical synonym. The limestone succession has a broad regional distribution and its associated sediments were deposited across the Baltoscandian platform in a shallow water epicontinental sea. Similar depositional conditions are not known today. The unit is remarkable in its near homogenous facies, lithologic and faunal composition throughout the platform. The most recent revision of trilobites from the Ceratopyge fauna recognized 36 species assigned to 28 genera (Ebbestad 1999).

    In the present study sequences at Ottenby and Degerhamn on southern Öland, Sweden, were logged and compared for trilobite biostratigraphy. In both investigated localities the resulting trilobite abundance distributions are very consistent. The trilobite fauna from the Bjørkåsholmen Formation in the Oslo Region, Norway, and Öland are composed of the same typical Ceratopyge assemblage. Trilobite abundance data from both areas are nearly identical and demonstrate an upward declination of trilobite specimens. Comparison across the Baltoscandian platform between the westernmost occurrences in the Oslo Region and the easternmost outcrops on Öland therefore suggests widespread stable conditions of the Ceratopyge fauna during the sedimentation of the Bjørkåsholmen Formation.

    Ebbestad, J.O.R. 1999: Trilobites of the Tremadoc Bjørkåsholmen Formation in the Oslo Region, Norway. Fossils and Strata 47. 118 pp.

    Owen, A.W., Bruton, D.L., Bockelie, J.F. Bockelie, T.G. 1990: The Ordovician successions of the Oslo Region, Norway. Norges geologiske undersøkelse Special Publication 4. 54 pp.

  • 287.
    Frisk, Åsa
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi. Paleobiologi.
    The Bjørkåsholmen Formation (Tremadoc): a homogenous distribution of trilobites throughout the Baltoscandian platform2004Ingår i: 48th Palaeontological Association Annual Meeting: Lille 2004, 2004, s. 199-Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The Bjørkåsholmen Formation (Tremadoc): a homogenous distribution of trilobites throughout the Baltoscandian platform

    Åsa Frisk

    Department of Earth Sciences, Palaeobiology, Uppsala University, Norbyvägen 22, SE-752 36 Uppsala, Sweden <asa.frisk@geo.uu.se>

    The Lower Ordovician succession of Baltoscandia is initiated by extensive carbonate deposition forming the Tremadoc Bjørkåsholmen Formation, formerly the Ceratopyge Limestone, a distinctive unit corresponding to the trilobite zone of Apatokephalus serratus. The limestone succession has a broad regional distribution and its associated sediments were deposited across the Baltoscandian platform in a shallow water epicontinental sea. Similar depositional conditions are not known today. The unit is remarkable in its near homogenous facies, lithologic and faunal composition throughout the platform. This is clearly demonstrated in the present study, where sequences at Ottenby and Degerhamn on southern Öland, Sweden, were logged and compared for trilobite biostratigraphy. In both investigated localities the resulting trilobite abundance distributions are very consistent. The trilobite fauna from the Bjørkåsholmen Formation in the Oslo Region, Norway, and Öland are composed of the same typical Ceratopyge assemblage. Trilobite abundance data from both areas are nearly identical and demonstrate an upward declination of trilobite specimens. Comparison across the Baltoscandian platform between the westernmost occurrences in the Oslo Region and the easternmost outcrops on Öland therefore suggests widespread stable conditions of the Ceratopyge fauna during the sedimentation of the Bjørkåsholmen Formation.

  • 288.
    Frisk, Åsa
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi. Paleobiologi.
    Trilobite biostratigraphy of the Tremadoc Bjørkåsholmen Formation on Öland, Sweden2004Ingår i: WOGOGOB-2004 Conference materials, 2004, s. 141-Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Trilobite biostratigraphy of the Tremadoc Bjørkåsholmen Formation on Öland, Sweden

    The Lower Ordovician of Baltoscandia is characterized by the initiation of extensive carbonate deposits of the Ceratopyge Limestone. The limestone succession has a broad regional distribution and its associated sediments were deposited in a shallow water epicontinental sea across the Baltic platform during the late Tremadoc (Jaanusson 1976, 1982; Dronov & Holmer 1999). Those particular depositional factors have no present day equivalents. The unit is definitely remarkable in its apparent homogenous facies, lithological and faunal composition. The significance of the Ceratopyge Limestone succession was early referred by numerous authors and recognized sedimentologically and stratigraphically. Tjernvik (1956) reinvestigated the Lower Ordovician beds in Sweden in detail and completed an account of the rich Ceratopyge fauna.

    In older studies a combined bio-litho stratigraphical concept of the unit has mostly been used, however a modern lithostratigraphical definition was given by Owen et al. (1990). The definition of the formation is based on the hypostratotype at Bjørkåsholmen in Slemmestad, Norway, and should be referred to instead of the historical synonym. The transition from the dark underlying Alum Shale Formation to the grey limestone beds marks the base of the Bjørkåsholmen Formation (BHF), this is evident in the change in not only lithology but also the typical associated fauna e.g. the Ceratopyge fauna (Tjernvik 1956; Ebbestad 1999). In Sweden the BHF is followed by the Hunneberg-Billingen Latorp Limestone and Volkhov Lanna Limestone. Shales of the Tøyen Formation follow the partially glauconitic limestone in Norway (Owen et al. 1990). The most recent revision of the trilobite fauna recognized 36 species assigned to 28 genera (Ebbestad 1999).

    The present study investigates trilobite distribution of the BHF in southern Öland, the easternmost outcrop of the formation. The underlying crystalline bedrock on Öland dips weakly to the east resulting in the exposition of the oldest overlying sedimentary rocks in the west and the youngest beds in the east (Jaanusson & Mutvei 1982). The upper Cambrian Alum Shale Formation is continued in the Lower Ordovician successions and is subsequently overlain by the upper Tremadoc limestone deposits represented by the BHF. Outcrops of this unit are fairly rare, confined to a few localities in the southern and south-central parts of the island.

    The material presented in this study was collected at the coastal section at Ottenby and at the Cementa quarry in Degerhamn. Sequences at Ottenby and Degerhamn were logged and material collected for a biostratigraphical study. To obtain trilobite abundances the sample frequency method (Jaanusson 1979; Nielsen 1995; Ebbestad 1999) was applied. The lower boundary of the BHF in Öland is marked by the occurrence of glauconiferous limestone nodules, represented in both localities. The main limestone beds in Öland, e.g. constituting continuous beds having the main trilobite abundance, are grey and micritic, and with some intercalations of glauconitic shale. In addition scattered grains of glauconite and small accumulations of pyrite are evident in the main limestone. The uppermost bed in the two successions, devoid in trilobites, marks the upper boundary of the formation, it is also exceptionally glauconitic suggesting slow deposition and starvation of sedimentation. The BHF at both Degerhamn and the Ottenby section has an approximately thickness of 0.6 meter and several discontinuity surfaces are evident.

    The trilobite abundance logs give a proposal for the distribution of the trilobite fauna during the upper Tremadoc in Öland. The material collected from the section in Degerhamn and Ottenby belongs to the Ceratopyge fauna and biostratigraphically the unit is connected to the Apatokephalus serratus Zone. The trilobite abundance distribution from each of the localities is very consistent. Additionally, the fossil assemblages in Öland and the Oslo Region (Ebbestad 1999) are built up by the same typical Ceratopyge fauna, indicating a correlation. Faunal signals show several similarities in the trilobite abundance data and both areas have an upwards declination of trilobite quantities in the sequences. Faunal distribution of trilobites of the Ceratopyge fauna is thus very coherent throughout the platform. This suggests widespread stable conditions of the fauna throughout the Baltic Platform during sedimentation of the BHF. The Central Baltoscandian Confacies Belt (Jaanusson 1976), to which Öland belongs, and the Oslo Region belonging to the Oslo Confacies Belt, demonstrate no facies differentiation of the platform until post-Tremadoc (Jaanusson & Mutvei 1982).

    The basal limestone nodules at the two investigated sections are devoid of trilobite remains. Periods of oxygenated lime mud sedimentation, reflected by the basal limestone nodules incorporated in the shale, may indicate times of fluctuations in the sea level. The main limestone units have little or no intercalations of shale, thus representing episodes of more stable sedimentary facies. The unstable settings may suggest non-favourable environments for the establishment of nileid communities (Fortey 1975), here represented by the Ceratopyge fauna, described by the absence of trilobites in the lowermost limestone nodules. Fluctuations of the sea level was probably confined to local settings and are suggested by extended periods with large inputs of oxygen during lime mud sedimentation. Constrained settings are most likely a result of diverse bottom topography and differences in current and wave distribution throughout the area (Ebbestad 1999). The faunal logs clearly demonstrate this idea. Ebbestad (1999) stated similar conditions for the depositions of the basal limestone beds in the BHF of the Oslo Region. The Ceratopyge fauna display coherent distribution in Öland and certainly across the platform, moreover, the distribution does not correlate with specific beds, presumably demonstrating dissimilar sedimentological developments of the two localities, suggesting that the deposition was diachronous.

    The upper Tremadoc and early Arenig represents a time of large global sea-level changes by the lowering of the seas (Fortey 1984), this event the Ceratopyge Regressive Event (CRE) (Erdtmann & Paalits 1995) could have resulted in the depletion of sediments. In Baltica this is clearly shown by the end of the Apatokephalus serratus zone, the top of the Bjørkåsholmen Formation, and in addition the disappearance of its associated Ceratopyge fauna.

    References:

    Dronov, A. & Holmer, L. 1999: Depositional sequences in the Ordovician of Baltoscandia. Acta

    Universitatis Carolinae - Geologica 43, 133-136.

    Ebbestad, J.O.R. 1999: Trilobites of the Tremadoc Bjørkåsholmen Formation in the Oslo Region,

    Norway. Fossils and Strata 47. 118 pp.

    Erdtmann, B.D. & Paalits, I. 1995: The Early Ordovician ’Ceratopyge Regressive Event’ (CRE): its

    correlation and biotic dynamics across the East European Platform. Lithuanian Geological Society,

    Geologija, 1994, 17, 36-57.

    Fortey, R.A. 1984: Global earlier Ordovician transgressions and regressions and their biological

    implications. In: Bruton, D.L. (ed.). Aspects of the Ordovician System. Palaeontological

    Contributions from the University of Oslo, No. 295, Universitetsförlaget, 37-50.

    Jaanusson, V. 1976: Faunal dynamics in the Middle Ordovician (Viruan) of Baltoscandia. In: Basett

    M.G. (ed): The Ordovician System. University of Wales Press, Cardiff, 301-326.

    Jaanusson, V. 1979: Ecology and faunal dynamics. In: Jaanusson, V., Laufeld, S. & Skoglund, R.

    (eds:): Lower Wenlock faunal and floral dynamics – Vattenfallet Section, Gotland. Sveriges

    Geologiska Undersäkning C 762, 253-294.

    Jaanusson, V. & Mutvei, 1982: Jaanusson, V. & Mutvei, H. 1982: Ordovician of Öland. Guide to

    exkursion 3. IV International Symposium on the Ordovician System, Oslo 1982, 23 pp.

    Nielsen, A.T. 1995: Trilobite systematics, Biostratigraphy and palaeoecology of the Lower Ordovician

    Komstad and Huk Formations, southern Scandinavia. Fossils and Strata 38. 374 pp.

    Owen, A.W., Bruton, D.L., Bockelie, J.F. Bockelie, T.G. 1990: The Ordovician successions of the

    Oslo Region, Norway. Norges geologiske undersøkelse Special Publication 4. 54 pp.

    Tjernvik. T.E. 1956: On the Early Ordovician of Sweden. Bulletin of the Geological Institutions of

    Uppsala 35, 108-284.

  • 289.
    Frisk, Åsa
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi. Palaeobiologi.
    Ebbestad, Jan Ove
    Uppsala universitet, Museer m.m., Evolutionsmuseet. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Diversity and distribution of paragastropods, tergomyans and gastropods in the Upper Ordovician Dalby Limestone, Sweden.2007Ingår i: Palaeontological Association 51st Annual Meeting: Uppsala University, Sweden, 2007, s. 1-Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
  • 290.
    Frisk, Åsa
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi. Paleobiologi.
    Holmer, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi. Paleobiologi.
    Linguliform and Craniiform Brachiopods from the Ordovician Tvären Crater, Sweden2005Ingår i: The 5th International Brachiopod Conference, Copenhagen, Denmark, 2005Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Linguliform and Craniiform Brachiopods from the Ordovician Tvären Crater, Sweden

    Åsa M. Frisk1 and Lars E. Holmer1

    1Department of Earth Sciences, Palaeobiology, Uppsala University, Norbyvägen 22, SE-752 36 Uppsala, Sweden

    During the Ordovician several bolides hit the Baltoscandian Epicontinental Sea. One of the impacts occurred at a water depth of 300 m and resulted in the 2 km wide Tvären crater, now situated in the Stockholm Archipelago, Sweden. The pre-impact sedimentary sequence at Tvären consisted of Ordovician carbonates resting on non-lithified sands of Early to earliest Middle Cambrian age. Following the impact event, deposition of carbonates continued (Dalby Limestone). The crater acted like a sheltering rim for the deposition of sediments, also displaying pure new settings for the fauna still living in the surrounding sea.

    The studied material from Tvären consists of glacial erratics from the area immediately southeast of the bay of Tvären on the coast of Södermanland. The limestone boulders are all fairly fossiliferous and have yielded numerous ostracods and brachiopods, the brachiopods being the next most common group; however the brachiopod fauna has never been previously studied in detail. The linguliform brachiopod fauna recorded from the erratic boulders include a large new lingulid genus and species, as well as new species of Schizotreta and Paterula. Eoconulus robustus Holmer is the only linguliform species previously recorded from the Dalby Limestone in Sweden.

  • 291.
    Frisk, Åsa
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi. Paleobiologi.
    Lindström, Maurits
    Holmer, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    A marine impact crater as an Ordovician ecosystem; the Tvären crater2005Ingår i: SEPM Research Conference; The sedimentary Record of Meteorite Impacts, 2005Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    A marine impact crater as an Ordovician ecosystem; the Tvären crater

    Frisk, Å.1, Lindström, M.2 & Holmer, L.E1

    1Department of Earth Sciences, Palaeobiology, Uppsala University, Norbyvägen 22, SE-752 36 Uppsala, Sweden, asa.frisk@geo.uu.se, lars.holmer@pal.uu.se

    2Department of Geology and Geochemistry, Stockholm University, Sweden, maurits.lindström@geo.su.se

    The Tvären crater was formed as a result of an impact in the Ordovician Baltoscandian epicontinental sea, now situated in the Stockholm Archipelago, Sweden. The bolide impact resulted in an approximately 2 km wide crater and the pre-impact sedimentary sequence consists of Ordovician carbonates resting on non-lithified sands of Early to earliest Middle Cambrian age. After the impact event and the settling of the impact ejecta and resurge material, deposition of carbonates continued (Dalby Limestone). The lithology and thickness of the post-impact Dalby Limestone vary depending on the depositional environment relative to the cratered seascape. The crater itself acted like a sheltering rim for the deposition of sediments, also causing a fairly rapid sedimentation rate compared to the normal sedimentation of the Dalby limestone. The area consequently displayed pure new settings for the marine fauna still living in the surrounding sea, though not affected by the impact, and thus creating a new ecosystem. This particular condition makes it possible to get a good precision of the sedimentation and faunal succession occurring in the crater. Drillings in the Tvären crater were conducted in 1991 resulting in an almost complete drill core through the sedimentary succession in the crater. The base of the core consists of crystalline breccia followed by resurge deposits and then the sedimentation of the Dalby Limestone. The post-impact fossil fauna mostly consists of chitinozoans, graptolites, trilobites, bryozoans, ostracodes, echinoderms, cephalopods and brachiopods. Certain groups are restricted to deeper or lower water levels, varying during the sedimentation, while some occur throughout the succession. A detailed biostratigraphy through the post-impact succession of the drill core is being conducted to understand how the abundance of species changed in relation to the varied environments and how the pre-impact faunal groups recovered gradually as life returned onto a sterile seafloor.

  • 292.
    Frisk, Åsa
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi. Paleobiologi.
    Lindström, Maurits
    Holmer, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi. Paleobiologi.
    Faunal recovery in the Ordovician Lockne and Tvären craters2005Ingår i: Lundadagarna i Historisk Geologi och Paleontologi IX, 2005Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    FAUNAL RECOVERY IN THE ORDOVICIAN LOCKNE AND TVÄREN CRATER

    Åsa Frisk1, Maurits Lindström2 & Lars Holmer1

    1Uppsala University, Department of Earth Sciences, Palaeobiology, Norbyvägen 22, SE-752 36 Uppsala, Sweden.

    2Stockholm University, Department of Geology and Geochemistry, SE-106 91 Stockholm, Sweden

    Limited amount of work has been carried out looking at the aftermath of marine impacts; in particular the patterns of faunal recovery in and around marine craters have never been studied in detail. In Baltoscandia several marine impacts occurred during the Ordovician, and this project focuses on the Lockne and Tvären craters. The Lockne crater in Jämtland, Sweden, is well exposed on land while the Tvären crater, located under water in the Stockholm archipelago, Sweden, is available as drill cores and erratic boulders. The impacted sedimentary sequence at Tvären consisted of Ordovician carbonates resting on non-lithified sands of Early to earliest Middle Cambrian age whereas at Lockne the same kind of limestone rests on Middle to Upper Cambrian bituminous mud. After the impact events and the settling of the impact ejectas and resurge materials, deposition of carbonates continued (Dalby Limestone).

    After impact the substrate became devoid of life. Large areas were affected by the local extinction of the fauna and thus provided virgin ground for the settling of marine fauna still living in the surrounding sea, though not affected by the impact. A dramatic alteration of the seafloor topography, caused by the impact, offered new habitats characterized by the crater morphology and sheltering rims. The immigrating biota, mostly consisting of chitinozoans, graptolites, trilobites, bryozoans, ostracodes, echinoderms, cephalopods and brachiopods, developed new ecosystems. Certain groups are restricted to deeper or lower water levels, varying during the sedimentation in the crater, while some occur throughout the succession. A detailed biostratigraphic study of the post-impact succession in the craters is being carried out in order to understand how the abundance of species changed in relation to the varied environments and how the pre-impact faunal groups recovered gradually as life returned onto a sterile seafloor.

  • 293.
    Frisk, Åsa
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi. Paleobiologi.
    Lindström, Maurits
    Paleobiologi.
    Holmer, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi. Paleobiologi.
    Palaeoecology of a marine impact crater in the Ordovician sea2005Ingår i: Palaeontological Association 49th Annual Meeting: University of Oxford, 2005Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Palaeoecology of a marine impact crater in the Ordovician sea

    Åsa Frisk1, Maurits Lindström2 and Lars Holmer1

    1Department of Earth Sciences, Palaeobiology, Uppsala University, Sweden

    2Department of Geology and Geochemistry, Stockholm University, Sweden

    The aftermath of marine impacts, in particular the patterns of faunal recovery in and around marine craters, are poorly understood. In the Ordovician Baltoscandian epicontinental sea a bolide impact resulted in the Tvären crater. At present it is located in the Stockholm archipelago, Sweden, where drillings in 1991 resulted in two drill cores.

  • 294.
    Frisk, Åsa M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Late Ordovician faunal distribution and ecospace partitioning in marine impact craters: the aftermath of the Lockne and Tvären event2010Konferensbidrag (Refereegranskat)
  • 295.
    Frisk, Åsa M.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi. Paleobiologi.